• at E9.5 cell proliferation in SM is reduced with cell mitotic indices decreased by 50% relative to controls; excessive cell death is detected from E8.5-9.5 in SM immediately distal to emerging outflow tract and in endoderm adjacent to the SM, with excessive cell death expanding into ventral pharyngeal endoderm by E9.5 but not in SM at this stage

• at E18.5, the distance between the lateral edge of the IHC and the medial edge of the first row OHC (a measure of the degree of PC development) is significantly decreased along the length of the cochlea

• at E18.5, PCs with weak or no lumenal projections are noted along the entire cochlear length with no region-specific variations

• at E18.5, the distance between the lateral edge of the IHC and the medial edge of the first row OHC (a measure of the degree of PC development) is significantly decreased along the length of the cochlea

• at E18.5, PCs with weak or no lumenal projections are noted along the entire cochlear length with no region-specific variations